Logging tool sonde sleeve

ABSTRACT

A logging tool for use in a wellbore having a sensor portion for making measurements. The tool has a sleeve enclosing the sensor portion and made of a material that is transparent to the measurements being made. One or more structural elements having physical characteristics different from the material comprising the sleeve are carried on the sleeve to enhance the mechanical properties of the sleeve.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of, and is acontinuation of, U.S. patent application Ser. No. 11/740,981, filed Apr.27, 2007 now U.S. Pat. No. 7,896,145, which claims priority to and thebenefit of U.S. Provisional Application No. 60/796,460, filed May 1,2006, both applications of which are hereby incorporated by referenceherein.

BACKGROUND

1. Field of Invention

The present invention pertains to logging tools for use in a wellbore,particularly logging tools having housings made of soft base materialrelative to the hardness of the wellbore wall or casing disposed in thewellbore.

2. Related Art

Logging tools are commonly used, in oil and gas exploration, forexample, to ascertain or infer properties of the subsurface formationsencountered by a wellbore. Logging tools may be used while drilling thewellbore, or may be run into the wellbore after drilling, for example,on a wireline. Various types of logging tools may be run, depending onthe measurement type. Such measurement types may include, but are notlimited to, resistivity, nuclear magnetic resonance (NMR), gamma ray,spontaneous potential, and dielectric constant.

Generally, the bulk of a logging tool is made of very strong material,such as steel. However, often a portion of the tool contains sensorsthat must communicate in some way with the surrounding environment. Forexample, resistivity sensors require electromagnetic signals to passinto and from the formation so that information characterizing theformation properties can be obtained. For the signals to pass into or bereceived from the formation, the sensors are preferably mounted on anelectromagnetically transparent medium. Such transparent media maycomprise composite, non-metallic materials. A disadvantage to thecomposite, non-metallic material is its relative softness compared tothe formation or casing. In many cases, that relative softness allowswear and tear of the sleeve to occur at an unacceptable high rate. Forexample, a NMR tool has powerful magnets that are strongly attracted tothe steel casing through which the tool must pass before reaching theuncased portion of the wellbore. The magnetic force causes the tool tobe dragged against the casing, causing scraping and wear.

SUMMARY

A logging tool for use in a wellbore having a sensor portion for makingmeasurements. The tool has a sleeve enclosing the sensor portion andmade of a material that is transparent to the measurements being made.One or more structural elements having physical characteristicsdifferent from the material comprising the sleeve are carried on thesleeve to enhance the mechanical properties of the sleeve.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a sleeve 10 in a tool assembly accordingto one embodiment of the present invention.

FIG. 2 is a side view of the sleeve 10 of FIG. 1.

FIG. 3 a shows schematically a top view of the reinforcement material inthe sleeve 10 of FIG. 1.

FIG. 3 b shows an enlarged view of one of the recessed areas in thereinforcement material of FIG. 3 a.

FIG. 4 shows a perspective view of a portion of the sleeve 10 of FIG. 1in which the recessed area has an overlapping material covering therecessed area.

FIG. 5 shows a cross sectional view of a sleeve 10 according to oneembodiment of the present invention in which the reinforcement materialis an insert disposed in receiving grooves in the sleeve 10.

FIG. 6 is a cross sectional view of a housing according to oneembodiment of the present invention in which the wall of the housing isthickened on one side.

FIG. 7 a shows a perspective view according to one embodiment of thepresent invention in which inserts are disposed asymmetrically aroundthe circumference of the sleeve 10.

FIG. 7 b shows a cross sectional view of a portion of the sleeve 10 ofFIG. 7 containing the inserts.

FIG. 7 c shows a cross sectional view of an alternative embodimenthaving a thickened wall on one side.

FIG. 8 is a schematic drawing showing an articulated pad in accordancewith one embodiment of the present invention.

FIG. 9 is a schematic drawing of a side view showing one of the pads ofFIG. 8.

FIG. 10 is a schematic drawing of a cross sectional view of the pad ofFIG. 9.

FIG. 11 is a plan view showing one embodiment according to the presentinvention in which a portion of the sleeve 10 allows signal to pass andanother portion blocks the passage of the signal.

FIG. 12 is a perspective, partially cut away view showing one embodimentaccording to the present invention in which the sleeve 10 has electrodesdisposed therein along with electrical connections to the electrodes.

FIG. 13 a is a perspective view showing a removable standoff ringconstructed in accordance with an alternative embodiment of the presentinvention

FIG. 13 b shows a cross sectional view of the removable standoff ring ofFIG. 13 a.

FIG. 14 shows an alternate embodiment in which the reinforcementmaterial comprises rings inserted into a sleeve in accordance with thepresent invention.

DETAILED DESCRIPTION

The invention pertains to a housing, sleeve, or enclosure 10 for adownhole tool 12 having a sonde or sensor section. The inventionprotects the tool's interior from the wellbore environment whilemaintaining a high degree of transparency to measurements being made. Tomaximize the protection, the enclosure has substantial mechanicalintegrity such that it is able to maintain its geometry as well as itsprotective qualities (i.e., resistance to wear and/or physicaldeterioration) for a substantial period (e.g., many trips in/out of thewell). Numerous logging tools contain a sonde or sensor section thatneeds a housing, sleeve 10, or enclosure that does not impede thepropagation or reception of the signal or energy being used for ameasurement. Such tools include, but are not limited to; MagneticResonance tools, Resistivity tools, Pipe Inspection/Corrosion tools,Radial/Axial/Tangential Cameras, and Magnetometer-based tools. Theprinciple of measurement may include signals or energy from one or moreof the following types: electrical, magnetic, electromagnetic, nuclear,acoustic, photo, etc. The present invention allows having such ahousing, sleeve 10, cover, etc. (transparent to elements ofmeasurements), but possessing better mechanical integrity.

Referring to FIG. 1, a non-conductive sleeve 10 made of a compositematerial, for example, is used to enclose the sonde section of a tool 12that transmits and receives an electromagnetic signal as a basis for itsmeasurement (e.g., magnetic resonance). A strong permanent magnet may bedisposed in such a tool 12. In such cases, as the tool 12 passes througha cased section of the well, it is pulled against the casing wall by theattractive magnetic force between the casing and the magnet. The axialsliding of the sleeve 10 against the steel casing while experiencing thesubstantial attractive transverse force produces significant wear on thesleeve 10. This wear can shorten the life of the sleeve 10, alter itsgeometry, reduce its mechanical integrity, and reduce its protectivequalities against the wellbore environment. The invention, in oneembodiment, uses bearing elements 14 (e.g., metallic skids, pads,buttons, etc.) having much tougher mechanical properties than the sleeve10 base material. The bearing elements are strategically located andembedded in the sleeve 10 base material so as to strengthen the sleeve10 and protect it against wear. The elements or inserts 14 perform theirmechanical function without affecting the physics of the measurement orthe placement of the tool 12 in the required section of the wellbore(i.e., non-intrusive geometry). The sleeve 10 can be run on a wireline,in TLC modes (Tough Logging Conditions—pipe conveyed logging) in whichmechanical loading is severe, and in D&M assemblies (Drilling andMeasurement—Logging While Drilling).

FIG. 2 shows a sleeve 10 made out of a thermoplastic composite or anyelectrically non-conductive material that includes several hard andstrong inserts 14. The inserts 14 provide wear resistance and strengthto the sleeve 10. The inserts 14 cover part or all of the axial lengthof the sleeve 10 and are positioned around the circumference, coveringthe sleeve 10 partly or fully. The inserts 14 may include overlaps 16 ofthe sleeve's material in several locations to secure the inserts 14 ontothe sleeve 10. The inserts 14 may have recessed areas 18 to allow forthe composite overlap 16, as shown in FIGS. 3 b and 4. The thickness ofthe sleeve 10 may also be increased where the inserts 14 are locatedsuch that those areas can provide standoff from the casing or wellborewall. Alternatively, the insert 14 may be trapped in the sleeve 10periphery by geometrical constraints 20, as shown in FIG. 5. Forexample, the insert 14 can have a large chamfer on each side to ensurethe inserts 14 are trapped in concave grooves 20 in the sleeve 10.

Other embodiments of the invention may include, singularly, inplurality, or in combination, embedded members 22 that are electricallyisolated electrodes used to measure wellbore properties (see FIG. 12).The measurement capability of an electrode 22 may be its primaryfunction or secondary to being a strengthening member. As astrengthening member, improvement in tensile and compressive loadbearing capacity may be had since those loads on the sleeve 10 areshared by the stronger elements. Besides having a generally more robustdesign for normal use, this can be important when running tools on drillpipe or during fishing operations. The inserts 14 can also improvebending strength to withstand loads experienced during transverseloading at the surface or in the well; for example passing through asevere dog-leg. An alternative embodiment to the reinforcement elements14 is having a section with a thickened wall 24, as shown in FIG. 6.Either embodiment leads to improved collapse resistance by increasingthe over-all yield strength to hoop stress. This may be critical if theenclosure is protecting sensitive internal components and the spacingbetween the enclosure and components is small.

The increased mechanical strength helps preserve the sleeve's outergeometry when subjected to flexure or wear. This is important, forexample, in cases in which maintaining the geometric shape of theenclosure is critical to maintaining measurement accuracy or to maintaina mechanical function such as seal integrity or interaction with otherparts. In addition, use of reinforcing inserts 14 or thickened wall 24improves resistance to changes in or degradation of mechanicalproperties due to temperature. Generally, for most materials, certainmechanical properties are diminished as temperature is elevated. This isespecially true for non-metallic materials such as composites,elastomers, etc. Placing reinforcing inserts 14 having higher resistanceto thermal effects in strategic areas can increase the enclosure'sover-all resistance to thermal effects. This is also true for chemicalresistance improvement. Improved shock or impact resistance can also beachieved by the present invention. That is, failures due to high strainrate can be reduced by strategic placement of the reinforcement inserts14. This may be particularly important at low temperatures (e.g., belowOF) where the elasticity (or modulus of elasticity) of non-metallicmaterials such as composites, elastomers, etc. decreases dramatically.

A further embodiment forces the tool 12 to self-orient in a certainazimuth or relative heading in the wellbore. By making one sector of thetool 12 heavier, the tool 12 can be forced to orient itself with theheavy side on the low side of the well. This can be achieved by eitherincreasing the wall thickness on one side of the housing 10 (FIG. 6) orby embedding inserts 14 of higher density on the desired heavy side, orboth.

The reinforcement inserts 14 can be made to extend beyond the outsidediameter of the housing 10, as shown in FIGS. 7 a and 7 b, to create adesired stand-off (gap) between the tool housing 10 and the wellborewall. This is particularly important for logging tools whosemeasurements require a particular stand-off. The embodiment in FIG. 7 cachieves the desired stand-off using a thickened wall 24.

In another embodiment (FIG. 14), the reinforcing inserts 14 can be rings26 that are placed at certain points along the length of the sleeve 10.These rings 26 are positioned along the length of the sleeve 10 inrelation to the sensors (not shown) that are located inside the sleeve10. The number and location of the rings 26 depends on the availablespace and mechanical requirements. Ultimately, the rings 26 should beplaced such that they have minimum interference with the sensormeasurement. In particular, it may be desirable to place the reinforcingrings 26 above and below the sensor section.

The sleeve 10 can also be protected by standoff sleeves 28 that generateenough space between the sleeve 10 and the borehole wall to prevent orto reduce sleeve wear. An embodiment of such a standoff sleeve 28 isshown in FIGS. 13 a and 13 b. The standoff sleeve 28 shown in FIGS. 13 aand 13 b can be designed to generate standoff between the front of thesensor, the back of the sensor, or any other side of the sensor. Thestandoff sleeve outer surface may be hardened to reduce wear. Thestand-off sleeves can carry measurement sensors that are connected toelectronics in the tool 12 similar to that shown in FIG. 12.

The standoff sleeve 28 of FIGS. 13 a and 13 b has grooves 30 betweenridges 32. These grooves 30 are designed to facilitate flow of wellborefluid and cuttings in the annulus of the wellbore. At least one standoffsleeve 28 is needed to generate the gap between the sleeve 10 and theborehole wall. The standoff sleeve 28 may be attached to the loggingtool 12 above or below the sensor section. Alternatively, the standoffsleeve 28 may be attached to the sleeve 10 in locations where it wouldhave minimum interference with sensor operations. In another embodiment,multiple standoff sleeves 28 may be used and placed above and below thesleeve 10, in addition to being deployed on the sleeve 10.

Improved vibration resistance can be achieved using reinforcementinserts 14. The inserts 14 can modify the natural or resonant frequencyof an enclosure 10. As such, the resistance to vibrate at a particularlyharmful frequency (e.g., during land transport) may be increased by thepresent invention.

Just as it is important to have measurement transparency in somesections of the housing, sleeve, cover, etc., it may also be importantto shield or shunt other sections to block the passage of signal. Theinvention, as shown in FIG. 11 and disclosed herein, may be implementedusing one or more inserts 14, for the purpose of shielding or shuntingthe signal (emission or reception) from the transmitters and/or sensors.This applies to all previously mentioned principles of measurement.

As mentioned above, in one embodiment the electrically conductive butisolated inserts 14 may be used solely as electrodes 22, or theirfunction may be combined for mechanical purposes. The application forsuch electrodes 22 or sensor terminals may include, but is not limitedto, measuring SP (Spontaneous Potential), making fast-responding wellfluid temperature measurements (for example, to detect leaks or inflow),and measurement of well fluid electrical properties such as resistivity(or its inverse, conductivity). There may also be cases in which anelectric potential, for example an electrical ground, needs to connectacross the non-conductive housing. Conductive inserts 14 may bestrategically placed in the non-conductive housing 10 and electricallyconnected at the required points to make an electrical connection. FIG.12 shows an embodiment in which a connector is embedded in the sleeve 10to electrically connect the electrode to, for example, a circuit board.

Situations arise in which the friction between a tool 12 and thewellbore wall needs to be reduced to successfully deploy (lower) thetool 12, particularly when the tool 12 is conveyed by wireline orslickline. Those cases may include high angle wells (say, greater than45-degrees inclination) and/or wells having high pressure relative tothe effective hanging weight of the tool 12. Tools with sondes havingnon-metallic housings typically have higher coefficients of frictionthan metallic housings, and hence have a more difficult time descendinginto the well. In the past, rollers were used to assist deployment. Theproblem with that option is the risk of failure is increased because therollers add length to the assembly and increase the number ofconnections that may fail. That option also adds cost. The presentinvention can solve the problem because the inserts 14 in thenon-metallic housings will reduce the coefficient of friction.

In another embodiment, the present invention may be implemented inlogging tools that contain a deployable sensor section 34 (e.g., a padconnected to an articulating mechanism). FIGS. 8-10 show one suchembodiment. The inserts 14 may be strategically placed in the pad 34 toimprove the mechanical properties of the pad structure, to improve wearresistance, and to serve as sensor electrodes.

While the invention has been described with respect to a limited numberof embodiments, those skilled in the art, having benefit of thisdisclosure, will appreciate that other embodiments can be envisionedthat do not depart from the scope of the invention as disclosed herein.Accordingly, the scope of the invention shall be limited only by theattached claims.

What is claimed is:
 1. A logging tool for use in a wellbore, comprising:a sensor portion for making measurements within the wellbore, whereinthe sensor portion communicates signals with a surrounding environmentas a basis for the logging tool measurements; a non-metallic sleevecomprising a longitudinal axis and enclosing the sensor portion, thenon-metallic sleeve being made of a material that is electromagneticallytransparent to the measurements being made by the sensor portion; andone or more structural elements carried by the non-metallic sleeve toenhance the mechanical properties of the non-metallic sleeve, whereinthe structural elements are supported about the non-metallic sleeve suchthat the non-metallic sleeve is positioned laterally between thestructural elements and the longitudinal axis, wherein the one or morestructural elements do not affect measurements made by the sensorportion of the tool, and wherein the one or more structural elements arelocated inside the non-metallic sleeve.
 2. The logging tool of claim 1,further comprising a standoff sleeve.
 3. The logging tool of claim 2,wherein the standoff sleeve creates a standoff between the non-metallicsleeve and a wall of the wellbore.
 4. The logging tool of claim 2,wherein the standoff sleeve comprises grooves, the grooves beingconfigured to facilitate flow of wellbore fluid and cuttings in anannulus of the wellbore.
 5. The logging tool of claim 1, wherein the oneor more structural elements comprise physical characteristics differentfrom the material comprising the non-metallic sleeve.
 6. The loggingtool of claim 5, wherein a thickness of the non-metallic sleeve isincreased at a location where structural elements are placed, such thatthe location provides standoff from a casing or wellbore wall, whereinthe one or more axially elongated structural elements comprise at leastone of metallic skids, pads, rings, and buttons, wherein thenon-metallic sleeve material is a composite, plastic, or ceramic,wherein the one or more structural elements are embedded in thenon-metallic sleeve, and wherein the one or more structural elementsmodify at least one of a resonant frequency of the non-metallic sleeveand an elasticity of the non-metallic sleeve.
 7. The logging tool ofclaim 1, wherein the one or more structural elements comprise at leastone of metallic skids, pads, rings, and buttons.
 8. The logging tool ofclaim 1, wherein the non-metallic sleeve material is a composite,plastic, or ceramic.
 9. The logging tool of claim 1, wherein the one ormore structural elements are metallic.
 10. The logging tool of claim 1,wherein the one or more structural elements are embedded in thenon-metallic sleeve.
 11. The logging tool of claim 1, wherein the one ormore structural elements are disposed inside an outer surface of thenon-metallic sleeve.
 12. The logging tool of claim 1, wherein the one ormore structural elements modify a resonant frequency of the non-metallicsleeve.
 13. The logging tool of claim 1, wherein the one or morestructural elements modify an elasticity of the non-metallic sleeve. 14.A logging tool for use in a wellbore, comprising: a sensor portion formaking measurements within the wellbore, wherein the sensor portioncommunicates signals with a surrounding environment as a basis for thelogging tool measurements; a non-metallic sleeve comprising alongitudinal axis and enclosing the sensor portion, the non-metallicsleeve being made of a material that is electromagnetically transparentto the measurements being made by the sensor portion; and one or morestructural elements carried on the non-metallic sleeve to enhance themechanical properties of the non-metallic sleeve, wherein the structuralelements are supported about the non-metallic sleeve such that thenon-metallic sleeve is positioned circumferentially between thestructural elements and the longitudinal axis, wherein the one or morestructural elements do not affect measurements made by the sensorportion of the tool, and wherein the one or more structural elements arelocated inside the non-metallic sleeve.
 15. A logging tool for use in awellbore, comprising: a sensor portion for making measurements withinthe wellbore, wherein the sensor portion communicates signals with asurrounding environment as a basis for the logging tool measurements; anon-metallic sleeve comprising a longitudinal axis and enclosing thesensor portion, the non-metallic sleeve being made of a material that iselectromagnetically transparent to the measurements being made by thesensor portion; and one or more structural elements carried on thenon-metallic sleeve to enhance the mechanical properties of thenon-metallic sleeve, wherein the structural elements are supported aboutthe non-metallic sleeve, wherein the one or more structural elements donot affect measurements made by the sensor portion of the tool, whereinthe one or more structural elements are located inside the non-metallicsleeve, and wherein a thickness of the non-metallic sleeve is increasedat a location where structural elements are placed, such that thelocation provides standoff from a casing or wellbore wall.